Emissions control systems and methods

ABSTRACT

Methods and systems are provided related to an emissions control system. The emissions control system has an exhaust after-treatment system defining a plurality of distinct exhaust flow passages through which at least a portion of an exhaust stream can flow, e.g., the exhaust stream is produced by an engine. The emissions control system also includes a controller for controlling injection of reductant into the exhaust stream flowing through each of the flow passages. In one example, the emissions control system is configured for use in a vehicle, such as a locomotive or other rail vehicle.

This application is a National Stage of International Application No.PCT/US10/61681, filed Dec. 21, 2010, which claims priority to U.S.Provisional Application Ser. No. 61/288,841, filed Dec. 21, 2009.

STATEMENT OF GOVERNMENTAL INTEREST

This invention was funded by Contract No. SDTC-2007-A-1207R-GOVT. TheUnited States Government has certain rights to this invention.

FIELD

The subject matter disclosed herein relates to vehicle emissions controlsystems and methods of operating emissions control systems.

BACKGROUND

Internal combustion engines generate various combustion by-products inthe exhaust gas during the course of engine operation. Under someconditions, it may be desirable to control the production (amount, rate,etc.) of one or more selected exhaust components. For example, undersome conditions, to meet stringent emissions criteria, it may bedesirable to control the production of NOx species and/or particulatematter (PM) in the exhaust gas.

Various engine configurations, fuel types, additives, and exhaustafter-treatment systems have been developed. As such, it may bedesirable to provide additional improvements in controlling the emissionof exhaust components. Furthermore, it may be desirable to design anemissions control system so that it can be installed in various vehiclesystems without losing emissions performance.

BRIEF DESCRIPTION

In one embodiment, an emissions control system includes an exhaustafter-treatment system defining a plurality of distinct exhaust flowpassages through which at least a portion of an exhaust stream can flow,e.g., the exhaust stream is produced by a vehicle engine or otherengine. The emissions control system further includes a control modulethat is configured to control the exhaust after-treatment system forinjecting an amount of reductant into the exhaust stream flowing througheach of the exhaust flow passages. By dividing the exhaust flow into aplurality of exhaust flow passages, and by adjusting the configurationof the emissions control system so that the plurality of exhaust flowpassages can be mounted on the engine and better accommodated in variousvehicle systems, the design of the exhaust after-treatment system can beimproved without degrading the emissions performance of the vehiclesystem.

DRAWINGS

The present invention will be better understood from reading thefollowing description of non-limiting embodiments, with reference to theattached drawings, wherein below:

FIG. 1 is a schematic diagram of an emissions control system accordingto an embodiment of the invention;

FIG. 2 shows clearance diagrams from commonly used North Americanlocomotive applications;

FIG. 3 shows a multi-leg emissions control system according to thepresent disclosure;

FIG. 4 shows a longitudinal view of the available packingvolume/envelop;

FIG. 5 shows a lateral view of the available packing volume/envelop;

FIG. 6A shows an example embodiment of the after-treatment system ofFIG. 3 with a burner;

FIG. 6B shows an example embodiment of the after-treatment system ofFIG. 3 without a burner;

FIG. 7A shows an example embodiment of the exhaust after-treatmentsystem of FIG. 3 configured with a rectangular substrate system;

FIG. 7B shows an example embodiment of the exhaust after-treatmentsystem of FIG. 3 configured with a cylindrical substrate system;

FIG. 8 shows example embodiments of flow diverters that may be used inthe emissions control system of FIG. 3;

FIG. 9A shows an example embodiment of an engine mounted supportstructure for the emissions control system; FIG. 9B is a partialcross-section view (not to scale) taken along line 9B-9B in FIG. 9A,according to another embodiment; FIG. 9C is a top plan view of an enginemounted support structure, according to another embodiment;

FIG. 10 shows an example embodiment of a platform mounted supportstructure for the emissions control system;

FIG. 11 shows an example embodiment of restrictions that may be includedin the middle leg of the emissions control system of FIG. 3;

FIGS. 12-15 show example engine cab configurations;

FIGS. 16A-16B show example embodiments of locomotive horn systems;

FIGS. 17A-17F show various embodiments of a urea tank walkway system,according to embodiments of the invention;

FIG. 18 is a schematic diagram of a multi-pump urea delivery system;

FIG. 19 is a perspective view of a reductant delivery system;

FIGS. 20-23 and 27 are schematic diagrams of several emissions controlsystems, according to other embodiments;

FIGS. 24-26 are various views of several embodiments of isolatorelements; and

FIG. 28 is a schematic diagram of a vehicle system having a walkway withreductant storage tank, according to another embodiment.

DETAILED DESCRIPTION

The methods and systems described herein relate to emissions controlsystems including an exhaust after-treatment system. In someembodiments, the invention relates to an emissions control system thatmay be configured for an engine in a vehicle. In other embodiments, theinvention relates to methods of operating such an emissions controlsystem. In still other embodiments, the invention relates to vehicleshaving the described emissions control system. With regard to thevehicle, any mobile asset capable of producing an exhaust stream mayutilize one or more aspects of the described invention. As anon-limiting example, a rail embodiment is disclosed herein. That is,the vehicle emissions control system is described in the context of alocomotive or other rail vehicle to facilitate the illustration ofseveral aspects of the invention. It will be appreciated that inalternate embodiments, for example, where the vehicle is a railcar,aircraft, automobile, or marine vessel, several of the constraints thatmay apply to a locomotive may not be applicable. However, the locomotiveenvironment is sufficiently challenging, such that many of the inventiveaspects of the described emissions control system can be showcased.

The designs of the emissions control system shown herein attempt tobalance and optimize multiple factors. As such, emphasis is given tothose designs that may be incorporated in vehicle embodiments with theleast impact. For example, in rail embodiments, emphasis is given todesigns that have reduced impact on locomotive performance, operatingcosts, and maintenance costs.

FIG. 1 illustrates a schematic diagram of an emissions control system100, in accordance with an embodiment of the invention. The emissionscontrol system 100 includes an exhaust after-treatment system 101coupled to (or configured to be coupled to) the exhaust manifold of anengine 10. The engine 10 is capable of producing an exhaust stream. Acontrol module 12, such as engine control unit (“ECU”), is configuredwith computer readable instructions (or otherwise configured) to adjustthe operation of various components (elaborated herein) of the exhaustafter-treatment system 101. The various exhaust after-treatmentcomponents of the exhaust after-treatment system 101 address the variouscombustion by-products released in the exhaust stream during operationof the engine 10. As shown in, and further elaborated with reference to,FIG. 3, the exhaust after-treatment system 101 may define a plurality ofdistinct, and in-line, exhaust flow passages through which at least aportion of the exhaust stream, received from engine 10, can flow. (Theexhaust flow passages and/or structure defining the passages are alsoreferred to herein as “legs.” A passage, the structure defining thepassage, and exhaust after-treatment component(s) associated with thepassage are sometimes referred to herein collectively as an “exhaustafter-treatment unit;” thus, teachings or description herein relating tothe legs specifically are also applicable to the exhaust treatmentunits.) The plurality of exhaust flow passages are positioned inparallel (or generally parallel) to each other. Furthermore, each of theplurality of exhaust flow passages may include each of the variousexhaust after-treatment components discussed herein. In one example, asdepicted, the engine 10 may be a boosted engine including a turbocharger118 (“Turbo”), coupled between an intake manifold and exhaust manifoldof the engine. The turbocharger 118 may be configured to provide aboosted aircharge to improve engine performance. Engine 10 may belocated within any suitable vehicle, such as a locomotive, aircraft,railcar, automobile, marine vessel, etc., or it may be part of a powergenerator or other stationary application.

In an embodiment, in each of the plurality of exhaust flow passages, theexhaust after-treatment system 101 includes a selective catalyticreduction (“SCR”) system 107 for reducing NOx species generated in theengine exhaust stream, and a particulate matter (“PM”) reduction system103 for reducing an amount of particulate matter generated in the engineexhaust stream. The various exhaust after-treatment components includedin PM reduction system 103 include a diesel oxidation catalyst 104(“DOC”), a diesel particulate filter 106 (“DPF”), and an optional burneror heater 102. The various exhaust after-treatment components includedin the SCR system 107 include an SCR catalyst 110, an ammonia slipcatalyst 112 (“ASC”), and/or a reductant component 108, such as astructure or region, for injecting, evaporating, mixing, and/orhydrolyzing an appropriate reductant used with the SCR catalyst, e.g.,urea hydrolysis. The reductant component 108 may receive the reductantfrom a reductant storage tank 116 (e.g., urea tank) and urea or otherreductant injection system 114.

Returning to the PM reduction system 103, the diesel particulate filter(DPF) 106 is configured to filter and remove particulate matter (PM)from the engine exhaust stream. Based on the PM load of the filter, theDPF 106 is periodically regenerated, for example, by burning off thestored PM, to restore the filter's PM storage capacity. In someembodiments, the DPF 106 may be optionally coupled to a regenerationdevice to assist in the periodic regeneration. For example, where theDPF 106 is a wall-flow type filter, and/or a ceramics-based filter, anappropriate regeneration device, such as the burner or heater 102, maybe coupled to the particulate filter. Herein, burner or heater 102 maybe configured to increase the temperature of the exhaust directedthrough DPF 106, for example, to a PM burn-out temperature. In anotherexample, where the DPF 106 is a flow-through filter, and/or ametallics-based filter, an additional regeneration device may not berequired. Example embodiments of a PM reduction system configured withand without an associated burner or heater are discussed herein withreference to FIGS. 6A-6B. A PM load of the DPF 106 may be inferred basedon engine operating conditions, such as an air-to-fuel ratio of theexhaust gas, duration of engine operation, etc. Alternatively, the PMload of DPF 106 may be estimated based on a pressure difference, acrossthe particulate matter filter, as sensed by one or more pressure sensorscoupled to the filter. Based on the estimated PM load, a control modulemay determine a regeneration timing and duration.

Diesel oxidation catalyst (DOC) 104 is coupled upstream of the DPF 106,in the direction of exhaust flow (as indicated by an arrow labeled“Exhaust flow”). DOC 104 catalytically reduces the amount of particulatematter in the exhaust gas that is directed into the DPF 106.Specifically, by using one or more catalysts, such as palladium andplatinum, exhaust PM is oxidized into carbon dioxide at DOC 104. Assuch, the DOC 104 may also oxidize other hydrocarbons and carbonmonoxide present in the engine exhaust into carbon dioxide and water. Bypositioning DOC 104 upstream of DPF 106, the PM load experienced by DPF106 can be reduced, thereby reducing the frequency of filterregeneration.

SCR system 107, coupled downstream of the DPF 106 portion of the PMreduction system 103, is configured to reduce exhaust NOx species.Specifically, exhaust NOx species are catalytically reduced by SCRcatalyst 110 into nitrogen and water. The SCR system 107 includes areductant injector for injecting an amount of an appropriate SCRreductant (e.g., urea) from a common reductant storage tank 116 (e.g., aurea tank) into an injection site 113 in a given exhaust flow passageupstream of SCR catalyst 110. By coupling the SCR catalyst 110downstream of injection site 113, the injected reductant may beappropriately mixed and hydrolyzed in structure (or region) 108 beforebeing absorbed on SCR catalyst 110. In rail and other dieselembodiments, the SCR reductant may be, or include, urea. For example,the reductant may be a diesel exhaust fluid (DEF), which is a solutionof water and urea. However, in alternate embodiments, the reductant maybe, for example, ammonia.

The reductant, e.g., urea, is stored in a common reductant storage tank116, e.g., a urea storage tank, and delivered into the exhaust flow ofeach of the plurality of passages of the exhaust after-treatment system101 via urea (or other reductant) injection system 114. The injectionsystem, as elaborated below, may include various delivery and returnlines, pumps, filters, and reductant injectors. Before use as areductant, urea is hydrolyzed (into ammonia and carbon dioxide) in ureamixing and hydrolysis structure (or region) 108. The ammonia absorbed onSCR catalyst 110 is used to reduce exhaust NOx species. Any excessammonia that slips from SCR catalyst 110 is absorbed and broken down byammonia slip catalyst 112, thereby reducing the ammonia content ofexhaust emissions. Example embodiments of a reductant storage tank andinjection system that can be used with the exhaust after-treatmentsystem 101 of FIG. 1 are described herein with reference to FIGS. 17-19.

A control module, such as engine control unit (ECU) 12, may receivesensor and communication signals from various sensors, such asthermocouples, pressure transducers, reductant (e.g., urea) levelsensors, one or more NOx sensors, temperature sensors, etc., positionedat various locations along the exhaust after-treatment system. Based onthe received sensor signals, the ECU 12 may operate one or moreactuators to adjust exhaust after-treatment system components. Forexample, the ECU 12 may receive input, from one or more temperaturesensors, regarding an exhaust gas temperature (EGT) at one or morelocations in the emissions control system, such as, upstream of heater102, upstream and downstream of DPF 106, and/or upstream and downstreamof SCR system 107. In one example, the exhaust gas temperature may beused to determine when, and for how long heater or burner 102 should beoperated. In another example, the ECU 12 may receive an input regardinga pressure difference (AP) across diesel particulate filter and mayinfer a PM load of the filter based on the estimated pressuredifference. The control module may use the inferred PM load to determinewhen to initiate a filter regeneration operation. In yet anotherexample, the ECU 12 may receive an input, such as a signal from a NOxsensor, regarding a NOx level in the exhaust gas upstream of the SCRsystem 107. Based on the indicated NOx level (e.g., as provided by theNOx sensor), the control module may adjust an amount of reductant (e.g.,urea) injection. In still another example, the control module maydetermine a duration of engine operation to periodically schedule acleaning of the emissions control system. In one example, where theengine is in a locomotive, the locomotive may be periodically cleanedusing hydrochloric acid (HCl) from HCl-based cleaning system 120.

In another example, where the exhaust after-treatment system includes aplurality of exhaust flow passages, the control module may be configuredwith code for dividing an exhaust stream from an engine into a pluralityof sub-streams, injecting a respective amount of reductant into each ofthe plurality of sub-streams (that is, each sub-stream is injected withits own amount of reductant), and chemically altering a determinedchemical component of the exhaust stream in response to the injectedreductant, wherein at least one of the plurality of sub-streams isrouted in a direction different from (e.g., opposite from) a routingdirection of one other of the plurality of sub-streams.

The exhaust after-treatment system 100 may similarly receive signalsfrom a switch box and controller area network (CAN) communications fromthe ECU 12. The exhaust after-treatment system may also communicate backto the ECU 12 and send response signals. In one example, a responsesignal may include a malfunction indication lamp (MIL) signalcommunicated to a switch box, or indicator box. In another example, thecontrols may include controlling the SCR system, for example, bycontrolling circulation, drainage, injection, and/or heating of urea orother reductant. Similarly, the PM reduction system may be controlled,for example, by controlling diesel fuel circulation, drainage,injection, active regeneration of the particulate filter, if soimplemented.

In one embodiment, the exhaust after-treatment system may include one ormore control modules (e.g., controllers), or sub-controllers/modules,communicating with ECU 12 for managing the various exhaustafter-treatment components of the after-treatment system. For example,there may be a first control module configured to control the PMreduction system, while another control module may be configured tocontrol the SCR system. In another example, such as where the exhaustafter-treatment system is configured with a plurality of legs, each legwith its own set of SCR system components, the exhaust after-treatmentsystem may include a single ‘DPF’ control module and multiple ‘SCR’control modules (for example, three SCR control modules in a multi-legafter-treatment system configured with three legs, one SCR controlmodule for each leg of the multi-leg system). However, such amultiple-control module system (herein, four-control module system) maybe relatively cumbersome to manage. Thus, in an alternate embodiment, asingle control module, configured with a larger number of input andoutput channels (I/O channels), can be used for both ‘DPF’ and ‘SCR’applications. In such embodiments, the control module count may besubstantially reduced, for example, to three or fewer control modules.

In another example, the exhaust after-treatment system may be coupled toat least an after-treatment control unit (ACU) dedicated to controllingand managing operation of the after-treatment system, while a fluidcontrol unit (FCU) is dedicated to controlling and managing thereductant (e.g., DEF). Herein, the after-treatment control unit (ACU)may include various sensors and actuators for controlling the exhaustafter-treatment system. The various sensors may include, for example,one or more temperature sensors to measure the exhaust temperaturethroughout the after-treatment system, one or more NOx sensors placed atthe exit of the after-treatment system, and one or more pressure sensorsto measure a pressure drop across components of the PM reduction system(such as the DOC and/or DPF) and across components of the SCR system(such as the SCR catalyst and/or the ASC). In one example, the ACU mayalso include a reductant injector control module to regulate injection(timing, amount, pressure, flow rate, duty cycle, etc.) of urea or otherreductant into the SCR system.

The ACU may be configured to receive messages from the ECU and may becapable of relaying a message back to the ECU, as needed. In oneexample, the ACU may be self-contained such that if a fault is detected,the control module can respond with an appropriate action withoutrequiring an input from the operator. In addition, the ACU maycommunicate with a switch box that is located in the operator cab, toallow manual shutdown of the system if desired. The switch box maycontrol power to the ACU, injectors, and pumps. In one example, whilethe system is designed to be self-contained, the manual shutdown featureenables the operator to manually override and shutdown the system, ifneeded.

In an embodiment, the fluid control unit (FCU) system controls fluiddelivery to the exhaust after-treatment system. The FCU system mayinclude, for example, one or more pumps to deliver the reductant (e.g.,urea) to the injectors and to circulate excess reductant back into thetank. Further, the FCU system may include one or more sensors to measurethe level of reductant in the tank as well as the temperature ofreductant in the tank. In one example, based on the temperature of thereductant in the tank, one or more heaters may be operated to maintainthe reductant at an optimum temperature and prevent freezing.

In one embodiment, one or more power supplies are provided. In oneexample, a total of three power supplies are provided. For example, afirst power supply can be used in conjunction with the ACU and adjoiningcomponents, while the second and third power supplies are used toprovide power to the FCU system.

In one embodiment, the after-treatment control system is configured tomeet the emission targets at 65% NOx reduction, 85% PM reduction, 85% COreduction, and 85% HC reduction. The control system may be furtherconfigured to meet US CFR 40.201 and 49.210 locomotive noise levelrequirements.

The emissions control system 100 of FIG. 1 may be used, for example, ina rail embodiment such as a locomotive. Therein, the design of theexhaust after-treatment system may be adjusted based on the amount ofclearance, or area/volume, available, around the locomotive enginewithin a locomotive engine cab. Turning to FIG. 2, map 200 shows variousclearance diagrams, with relation to engine 210 positioned within enginecab 201 for commonly used North American locomotive applications.Specifically, map 200 shows a first clearance diagram 202 for a “Plate Cwith exception area” configuration (dashed line)(“Plate C”) and a secondclearance diagram 204 for a “Plate L” configuration (solid line)(“PlateL”). As such, Plate L is the larger of the two plates and is applicableon locomotives operated in most of the US and Canada. The slightlysmaller Plate C is used for selected corridors in the northeastern USwhere some tunnels are slightly smaller. As indicated, Plate C has anexception area 206 which accounts, at least in part, for it being morerestrictive. Most locomotives used in North American operations arebuilt to fall within the first clearance diagram of the more restrictivePlate C, while fewer locomotives are built to fall within the secondclearance diagram of the less restrictive Plate L.

The exhaust after-treatment system of the present disclosure has beendesigned to include all the components required to address exhaustemissions while taking into account the packaging volume available for agiven plate configuration. As shown in FIGS. 3-5, packaging volume 401is defined as the space available above engine 210 and within the chosenclearance diagram (herein, depicted for Plate C) while maintaining spacefor remaining cab structures (including current cab width and length),clearance, and any other necessary structures. FIG. 4 shows alongitudinal view 400 of the packaging volume 401 available for a PlateC 402 configured locomotive. Height requirements for mounting structure408 coupled with manufacturing tolerances, further constrained byoriginal packaging volume, challenge the incorporation of all thecomponents of the exhaust after-treatment system within the Plate Cclearance diagram. Necessary clearances and structures include anexternal clearance 406 (for example, 1″/˜2.5 cm long), a cab structure404 (for example, 3″/˜7.5 cm long), and a mounting structure 408 (forexample, 5.5″/˜14 cm long).

FIGS. 3 and 5 show alternate views (300 and 500, respectively) of thepackaging volume 401, or envelope, available within which exhaustafter-treatment system 302 is designed to fit. Specifically, the exhaustafter-treatment system of the present disclosure is designed to fitwithin packaging volume 401 when mounted over the exhaust manifold ofengine 210. Exhaust after-treatment system 302 is designed to include aplurality of in-line exhaust flow passages, or legs 304, though which atleast a portion of the exhaust stream can flow. The exhaustafter-treatment system is mounted on engine 210 via a mounting structure(not shown) such that a longitudinal axis 306 of the after-treatmentsystem is aligned in parallel (or generally parallel) to a longitudinalaxis 308 of engine 210. In the embodiment where the engine is alocomotive engine housed in an engine cab, the engine may be positionedwithin the cab such that the longitudinal axis of the after-treatmentsystem is aligned in parallel (or generally parallel) to thelongitudinal axes of both the engine and the engine cab.

In the depicted embodiment, exhaust after-treatment system 302 is shownas a multi-leg system with three legs 304, wherein each leg 304represents a single in-line flow passage of exhaust after-treatmentcomponents. Specifically, each leg 304 of the multi-leg exhaustafter-treatment system 302 enclosed within packaging volume 401 has acomplete set of all the exhaust after-treatment components, includingall components of the SCR system and the PM reduction system.

The plurality of exhaust passages, or legs, 304 of the exhaustafter-treatment system 302 are configured to receive at least a portionof the exhaust stream from an exhaust outlet of engine 210 via atransition section 310. To achieve this function, transition section 310turns the exhaust flowing from the single turbocharger outlet into thethree inputs of the after-treatment system legs 304. As such, thisturning has to be accomplished in a very short flow length and with asharp turn radius, with a minimum loss of exhaust pressure. At the sametime, it is desired to provide an even flow distribution into all threelegs so as to increase emissions control system performance. Thus, inone embodiment, as depicted in FIG. 11, transition section 310 isconfigured with one or more appropriately designed restrictions.Specifically, transition section 310 is outfitted with a restrictionplate 1102 that includes a restricting orifice for a middle leg of theexhaust after-treatment system. That is, by way of the plate 1102, aflow aperture 1104 between the transition section 310 and the middle legis narrower than flow apertures 1106 between the transition section andother legs. Depending on the internal configuration of the transitionsection 310, each of the openings (between the transition section andlegs) may be different sized, or they may be the same size, or some maybe the same size and others different. Restriction(s) may beappropriately designed, to increase flow uniformity, through empiricaltesting, flow modeling, etc. based on the internal shape/configurationof the transition section, the flow output range of the engine exhaust,and the configuration(s) of the exhaust passages/legs. Restrictionplates may be fitted from outside to further control the flow throughthe legs.

In one embodiment, shown in FIG. 9A, the plurality of exhaust flowpassages 904 include a first, a second, and a third exhaust passage withthe second exhaust flow passage (or middle leg) nested between the firstand third exhaust flow passages (or outer legs). Considering that themiddle region of the exhaust outlet passage (through the transitionsection 310) may tend to receive the bulk of the exhaust flow, using arestriction plate 1102 for the middle leg (that restricts flow from themiddle region of the engine exhaust outlet to the middle leg of theexhaust after-treatment system) may facilitate better exhaustdistribution between the middle and outer legs of the exhaustafter-treatment system. In this way, by including one or morerestrictions, the restricted transition section may provide improvedflow distribution with minimum pressure loss at an acceptablecombination of cost, performance, and structural strength. In anembodiment, the transition section 310 provides a flow uniformityvariation of <1%.

As shown in FIGS. 3 and 5, designing the exhaust after-treatment systemas a multi-leg (herein, depicted with three legs) control system designalso enables a smaller profile volume for the exhaust after-treatmentsystem. The lower profile after-treatment system also has a reducedcatalyst volume. The reduced volume allows the Plate C clearance diagramto be maintained, and maximizes the potential application of the exhaustafter-treatment system as a retrofit product. Furthermore, maintainingcurrent control system design and packaging volumes may allow for reuseof Plate C to Plate L clearance diagrams, if desired.

As shown in FIG. 1, the exhaust after treatment system may include a PMreduction system 103 with several exhaust after-treatment components,such as a diesel particular filter (DPF) 106. As such, variousconfigurations may be possible for DPF 106 in the exhaustafter-treatment system. For example, one or more wall-flow dieselparticulate filters with one or more associated burners or heaters canbe used. Alternatively, one or more flow-through diesel particulatefilters can be used. FIG. 6A depicts a first embodiment 600 wherein eachleg 304 of multi-leg after-treatment system 302 includes a PM reductionsystem configured with a wall-flow diesel particulate filter 606 and anassociated regeneration system including a burner or heater 602,upstream (in the direction of exhaust flow) from the diesel oxidationcatalyst 604 and SCR system 607. FIG. 6B depicts a second embodiment 650wherein each leg 304 of exhaust after-treatment system 302 is configuredwith a flow-through diesel particulate filter 656 coupled to the dieseloxygen catalysts. In this embodiment, an associated burner is notrequired, thereby allowing relatively more working volume to beavailable. Additionally, in such an embodiment, the likelihood of roadfailures of the locomotive, such as due to burner problems or cloggingof the particulate filter, are reduced. Further still, NOx reduction andparticulate matter (PM) reduction is improved with the use of thecoupled diesel oxygen catalyst and flow-through filter (FTF) approach inthe PM reduction system.

Each of the plurality of exhaust flow passages, or legs, is defined by adistinct substrate 605 (or set of substrates) through which the exhauststream can flow. The substrate material used can include, for example,metallic or ceramic bases. Embodiments using metallic bases tend to bemore robust, and are available in more complex configurations. Incomparison, embodiments using ceramic bases tend to be more chemicallyand thermally stabile and have relatively lower substrate corrosion inthe presence of high-temperature exhaust and ammonia.

The shapes of substrate 605 may also be varied. In one example, asillustrated in embodiment 700 of FIG. 7A, the substrate 605 of each leg304 of exhaust after-treatment system 302 is rectangular shaped. Inanother example, as illustrated in embodiment 750 of FIG. 7B, thesubstrate 605 of each leg 304 of exhaust after-treatment system 302 iscylindrically shaped. The cylindrical substrates depicted in FIG. 7B maybe structurally stronger than other shapes made of extruded ceramicsubstrates. Thus, given the harsh noise, high impact, and vibrationsexperienced in the locomotive environment, cylindrical forms may beadvantageously used in rail embodiments. In alternate, less harshapplications, rectangular or cube shaped substrate systems may be used.

Use of cylindrically shaped substrates may also enable a furtherreduction in catalyst volumes compared to other possible shapes.Specifically, as shown in FIG. 7B, each leg of the multi-leg exhaustafter-treatment system can be further divided into a plurality ofsub-legs (herein, shown as three sub-legs), which may be nested forfurther compaction. Thus, in the short flow lengths available in theafter-treatment system of the rail embodiment, flow distribution may beimproved by using cylindrically shaped substrates, thereby alsoimproving engine and locomotive performance.

FIG. 7B depicts a first example embodiment wherein each of the plurality(herein three) of cylindrically-shaped exhaust flow passages, or legs304, is further divided into a plurality (herein three) of distinct,cylindrically-shaped exhaust flow sub-passages 704. The exhaust flowsub-passages 704 for each leg 34 are arranged with at least somesub-passages on an upper level 706 immediately above at least some othersub-passages on a lower level 708. That is, for a given exhaust flowpassage (or leg), a first number of sub-passages are on top of a secondnumber of sub-passages. This configuration enables a further compactionupon nesting of neighboring exhaust flow passages, thereby providingpackaging advantages. For example, a first exhaust flow passage 754 maybe configured with a smaller number (herein one) of sub-passages 704 onthe upper level 706 and a larger number (herein two) of sub-passages 704on the lower level 708. A second exhaust passage 756 may be configuredwith a larger number (herein two) of sub-passages 704 on the upper level706 and a smaller number (herein one) of sub-passages 704 on the lowerlevel 708. A third exhaust flow passage 758 may also be configured witha smaller number (herein one) of sub-passages 704 on the upper level 706and a larger number (herein two) of sub-passages 704 on the lower level708. The first, second, and third exhaust passages are then aligned suchthat the second exhaust flow passage 756 (herein also referred to asmiddle leg) is nested between the first and third exhaust flow passages754, 758 (herein also referred to as outer legs). In other words, thecylindrical shape of the substrates allows the sub-passages of themiddle leg to be inverted (along a top to bottom axis) with respect tothe sub-passages of each of the neighboring outer legs 754, 758. Thisconfiguration provides for desirable space utilization, while thecommonality of parts provided by this configuration reducesmanufacturing and component costs.

To further enable substantially uniform flow distribution through theexhaust flow passages of FIG. 7B, a region of the transition section(310, FIG. 11) coupled to the second exhaust flow passage 756 (or middleleg) may be configured with more restrictions (1102, FIG. 11) than theregion of the transition section coupled to the first and third exhaustflow passages (or outer legs).

Optionally, one or more flow diverter systems may be employed with thesubstrate systems of FIGS. 7A-B, for diverting flow through theplurality of exhaust flow passages of the exhaust after-treatmentsystem. FIG. 8 shows a first example embodiment of a flow diverter 800that comprises a first flow diverter configuration 802. FIG. 8 alsoshows a second example embodiment of a flow diverter 850 that comprisesa second flow diverter configuration 804. In the case that thenaturally-occurring flow distribution is not sufficiently distributedacross the faces of the catalyst substrates, additional flowdiverters/baffles can be employed to spread the exhaust.

In the case of a rail embodiment of the emissions control system of thepresent disclosure, the mounting of a large and heavy exhaustafter-treatment system onto a locomotive engine involves addressingspace restrictions and material capabilities. For example, the heavyweight and large size of the exhaust after-treatment system does notallow for the use of relatively simple elastic hangers or clamp ringsthat might otherwise be acceptable for use in automotive applications.Additionally, a mounting structure used for the exhaust after-treatmentsystem has to account for longitudinal expansion given the significantthermal expansion experienced by exhaust after-treatment systemcomponents. The mounting structure should also be able to withstandrelatively high longitudinal shock loads that may be experienced duringlocomotive coupling. At the same time, the mounting structure shouldhave low impact on the maintainability of the engine while being easy toinstall and remove from the locomotive.

Various selection criteria may be used to address various applicationspecific design concerns. For example, where the after-treatment systemis mounted on the locomotive engine or locomotive cab platform, theseselection criteria may include buff load capability of the engine and/orplatform, effect of mechanical vibrations on the after-treatment systemand related mounting structures (and sub-structures), impact ofmechanical vibrations on the reliability of other components in thevehicle (such as, other locomotive components), effect onmaintainability (such as, for routine maintenance operations) due toengine and/or platform mounting, ease of modification and restoration ofthe locomotive, costs, emissions performance, etc. For example, anengine-mounted after-treatment system may be used on locomotives if thespecific application has less-significant on-engine vibration signaturesand the buff/coupling loads of the locomotive are more significant,while a platform-mounted emissions control system may be used onlocomotives if engine vibrations are very substantial, but buff/couplingloads are less severe or less frequent. Thus, based on the selectedcriteria, the mounting of the after-treatment system (e.g., position,location, height, structures used for mounting) may be varied. In oneexample, based on the above-mentioned criteria, a locomotive may befitted with an engine-mountable exhaust after-treatment system, as shownin FIG. 9A. In another example, based on the above-mentioned criteria, alocomotive may be fitted with a platform-mounted after-treatment system,as elaborated upon in FIG. 10.

One example of an engine-mountable after-treatment system 900 isdepicted in FIG. 9A. The engine-mountable after-treatment system isdesigned to provide the desired stability and strength. In the depictedembodiment, exhaust after-treatment system 902 includes a plurality ofdistinct exhaust flow passages 904, wherein each of the plurality ofdistinct exhaust flow passages 904 is configured to receive at leastsome exhaust gas from an exhaust manifold (also referred to as theexhaust outlet) 906 of engine 210. (In FIG. 9A, for simplicity ofillustration, the distinct exhaust flow passages 904 are not shownconnected to the exhaust manifold 906; however, when the system 900 isdeployed for operation, the distinct exhaust flow passages 904 would beconnected to the exhaust manifold 906 by way of a transition section,such as section 310 shown in FIG. 3.) Engine 210, herein, is alocomotive engine configured to be positioned in an engine cab (FIG. 12)of the locomotive. The exhaust after-treatment system is mounted onengine 210 such that a longitudinal axis 306 of the after-treatmentsystem 902 is aligned in parallel (or generally parallel) to thelongitudinal axis 308 of engine 210. The plurality of distinct exhaustpassages 904 are aligned in parallel (or generally parallel) to eachother and in parallel (or generally parallel) to the longitudinal axis306 of the after-treatment system 902.

Exhaust after-treatment system 902 is mounted on engine 210 via anengine-mounted support structure 910. Engine-mounted support structure910 includes a base 912 and a plurality of mounting legs 914. One end916 of each mounting leg 914 is coupled to a lower surface of the base912, while another, opposite end 918 of each mounting leg 914 is coupledto the engine 210 at one of a plurality (e.g., four) of mountinglocations 920. The plurality of mounting locations 920 includes at leastsome locations on an engine frame 922 of engine 210, and at least somelocations on a front end 924 (e.g., front end cover) of engine 210. Thebase 912 may include cross-members, attached to and extending betweenthe peripheral edge member(s) of the base, for enhanced rigidity. Thebase 912 may be substantially rectangular (although other shapes arepossible), and the plurality of mounting legs 914 may be ofsubstantially equal height, although this will depend on the mountinglocations (that is, if one of the mounting locations is lower than theothers, with respect to a distance from the desired position of thebase, then the leg for attachment to the lower mounting location will belonger than the others).

The exhaust after-treatment system 902 may be mounted to theengine-mounted support structure 910 in several ways. For example, thesupport structure 910 may include a plurality of vibration isolators 915to which the after-treatment system 902 is mounted, for providingvibration and shock load isolation for each leg of the exhaustafter-treatment system (and thereby improving system stability). FIG. 9Bshows one example of a possible configuration, according to anembodiment of the invention. Here, the engine-mounted support structure910 further includes a plurality of support members 926. The supportmembers 926 are welded or otherwise attached to the top of the base 912,and provide support and attachment points for a plurality of isolators915, shown schematically in this view. There may be one support member926 for each isolator 915 (as generally shown in FIG. 9B), or thesupport members 926 may be strip-like plates that extend across oppositeparallel sides of the base 912 for supporting two or more isolators (asindicated by lines 917). The isolators 915 are bolted or otherwiseattached to the support members 926. In turn, mounting brackets 919 ofthe after-treatment system 902 are bolted or otherwise attached to theisolators 915. The mounting brackets 919 hold the after-treatment system902 above the support structure 910, and act as attachment points of theafter-treatment system 902 to the isolators 915 or otherwise to thesupport structure 910. (The mounting brackets 919, or similarstructures, are not shown in FIG. 9A, for the sake of simplicity ofillustration.) In an embodiment, with reference to FIG. 9C, eachdistinct leg 904 of the after-treatment system 902 includes plural(e.g., four) mounting brackets 919, which are spaced apart along thelength of the leg 904, and is attached to the base 912 by acorresponding number (e.g., four) of isolators 915. Thus, in thedepicted three-leg exhaust after-treatment system 902, the system 902 isattached to the support structure 910 at twelve supporting points 928,which provide vibration and shock load isolation for the exhaustafter-treatment system.

To address thermal expansion of the after-treatment system, acombination of first and second, different types of isolators may beused, for example, a combination of relatively stiff isolators andrelatively soft isolators. Alternatively and/or additionally, theisolators are metallic isolators (meaning the isolators include a metalelement that performs a vibration/isolation function). In oneembodiment, all the isolators are metallic isolators. The variousmetallic isolators can include a plurality of relatively stiff metallicisolators 915 a, for example, wire mesh isolators, used at the pointswhere the legs 904 are attached at the engine front end 924. In oneexample, for a system with three legs 904, three such relatively stiffmetallic isolators 915 a are present in the mounting structure (e.g.,one such isolator for each leg). The various metallic isolators mayfurther include a plurality of relatively soft metallic isolators 915 b,for example, cable-mounted isolators (also known as cable isolators),used at all other locations of the mounting structure. (The isolatorsare generally referred to by element number 915; specific types ofisolators by 915 a, 915 b, etc.) In one example, for a system with threelegs 904, nine such relatively soft metallic isolators 915 b are presentin the mounting structure. In such a configuration, the wire meshisolators handle buff load (e.g., longitudinal force), while thecable-mounted isolators handle the thermal expansion of the exhaustafter-treatment system. In this way, both types of isolators work inparallel to isolate the after-treatment system from the effects ofengine vibrations.

An example of a platform mounted emissions control system 1000 isdepicted in FIG. 10. In this embodiment, the exhaust after-treatmentsystem 1002 is mounted above the locomotive engine 210 via aplatform-mounted support structure 1004. The support structure 1004includes a substantially rectangular base 1006 coupled to a locomotiveplatform 1008 via a plurality of vertical posts 1010 of substantiallyequal length. (For example, in an embodiment, the base is level.) Theplurality of vertical posts 1010 are further coupled to each other via aplurality of angled stiffening bars 1012. As a non-limiting example, thedesign depicted in FIG. 10 utilizes three vertical posts 1010 on eachside of the locomotive. Isolation from shock and vibration is addressedthrough vertical posts 1010, as well as through a plurality of vibrationisolation support points 1014 (e.g., isolators, as explained elsewhereherein), though the inputs to the different posts and support points mayvary in magnitude and frequency based on their position. In one example,the plurality of vertical posts 1010 are evenly distributed along thelength of the locomotive cab (as shown), although in alternateembodiments, based on the configuration of the locomotive cab, a largernumber of vertical posts 1010 may be provided at one end of the supportstructure as compared to the other end of the support structure 1004.The vibration isolation support points 1014 may be positioned at variouslocations based on where in the engine 210, or engine cab, vibrationsare most likely to be experienced, and further based on an amount ofvibration expected. For example, at least some vibration isolationpoints 1014 may be positioned between an upper surface of the base 1006and the substrate of each leg of the exhaust after-treatment system1002. Additional vibration isolation points 1014 may be positionedbetween a lower end of each vertical post 1010 and the platform 1008. Inthis way, the depicted platform-mounted exhaust after-treatment systemaccounts for the moments involved with the large size and heavy mass ofthe after-treatment system mounted on the tall structure of thelocomotive.

In an embodiment, an emissions control system includes a supportstructure and an exhaust after-treatment system. The support structureis at least partially positioned above an engine. (The engine is capableof producing an exhaust stream.) The exhaust after-treatment system hasat least one exhaust after-treatment unit through which at least aportion of the exhaust stream is directed to flow. Each exhaustafter-treatment unit has at least one exhaust after-treatment componentfor treating the portion of the exhaust stream flowing through the unit.The at least one exhaust after-treatment unit is attached to the supportstructure and positioned above the engine. Additionally, the engine issupported on a platform, and the support structure is attached to theplatform.

In an embodiment, an emissions control system includes a supportstructure and an exhaust after-treatment system. The support structureis at least partially positioned above an engine. (The engine is capableof producing an exhaust stream.) The exhaust after-treatment system hasat least one exhaust after-treatment unit through which at least aportion of the exhaust stream is directed to flow. Each exhaustafter-treatment unit has at least one exhaust after-treatment componentfor treating the portion of the exhaust stream flowing through the unit.The at least one exhaust after-treatment unit is attached to the supportstructure and positioned above the engine. The engine is housed in anengine cab. The at least one exhaust after-treatment unit is attached tothe support structure and positioned above the engine such that alongitudinal axis of the at least one exhaust after-treatment unit is atleast generally parallel to a longitudinal axis of the engine and alength of the engine cab.

In some rail embodiments, due to the complex shape and size of theexhaust after-treatment system, as it extends above the original enginecab, the design of the engine cab is also modified to better protect andsupport the mounted exhaust after-treatment system. It will beappreciated that the engine cab design for a given locomotive may beselected based on a variety of criteria such as accessibility to enginecab components, and ease of manufacturing. Various example engine cabdesigns are now discussed with reference to FIGS. 12-15.

A first example embodiment of an engine cab 1202 of locomotive 1201housing a locomotive engine and an exhaust after-treatment system isdepicted in FIG. 12. Engine cab 1202 is defined by a roof assembly 1204and side walls 1206. Engine cab 1202 is shown with several interfacesfor communicating with other cabs and components of locomotive 1201.Engine cab 1202 is configured to protect an enclosed exhaustafter-treatment system (not shown), an engine housed within the cab, andauxiliaries from rain, snow, dust, wind, sun, and inclement weatherconditions. Engine cab 1202 is also configured to support a horn system1204, lighting (if present), and power outlets. The design of engine cab1202 enables operating personnel to be protected from hot surfaces androtating parts while also enabling the cab to support maintenancepersonnel on the roof.

The horn system 1204 may include one or more horns positioned above theengine within locomotive engine cab 1202, at a front end 1216 (hereinalso referred to as #2 end) of the engine cab 1202 between theafter-treatment system and a front wall (not shown) of the cab, an openend of at least one horn facing towards the center 1218 of the enginecab 1202.

In the depicted embodiment, engine cab 1202 is designed with a completeuniformity of appearance, and with a locomotive exterior. Additionally,multiple interfaces are provided. These may include, for example, aninterface communicating with a urea tank 1207, an interfacecommunicating with blower cab 1208, an interface interacting withradiator cab 1210, and an interface for a rail platform (not shown). Theengine cab 1202 and the several interfaces are designed so as to providesufficient clearance to allow for significant thermal variations in theexhaust after-treatment system while having minimal impact on themaintainability of the after-treatment system and the engine. In oneexample, this is achieved by positioning the interface between theengine cab 1202 and urea tank 1207 on the A side walkway 1212, while theurea tank 1207 is bolted to the platform 1214 of the locomotive.

FIG. 13 shows an alternate view of the engine cab 1202 of FIG. 12. Asshown, roof assembly 1204 of engine cab 1202 includes a plurality ofroof panels 1302 hingedly-attached to a side wall 1206 of the cab suchthat the exhaust after-treatment system is accessible through at leastone of the plurality of hingedly-attached roof panels 1302. In thedepicted embodiment, the hingedly-attached roof panel 1304 at the frontend 1306 (herein also referred to as the #2 end) is a separable assemblyand can be a bolt-on type hatch arrangement just above the turbocharger(not shown). The engine cab 1202 is designed to accommodate a hornsystem (such as horn system 1204 of FIG. 12). A hinged hatch assembly isalso included which can be opened to 90 degrees to facilitatemaintenance of the exhaust after-treatment system and/or its components.

FIG. 14 shows an alternate embodiment of an engine cab 1400 wherein theroof assembly 1401, at the front end 1216 of the engine cab, is splitinto a plurality (herein three) of hingedly-attached roof panels 1402,1404, and 1406 of substantially equal dimensions. However, in alternateembodiments, the dimensions of the different panels may be different. Inthe depicted embodiment, no hinges or latches are provided. Instead, thedifferent roof panels are bolted to the sidewalls. Herein, roof panels1402, 1404, 1406 cover the entire width of the engine cab, thusproviding more accessibility to the exhaust after-treatment system andits components.

FIG. 15 shows another example embodiment of an engine cab 1500 whereinthe plurality of roof panels of roof assembly 1502 includes a firstlarger panel 1504 and a second smaller panel 1506. Herein, roof panels1504 and 1506 both are bolt-on roof panels, or hatch assemblies.Specifically, the first larger roof panel 1504 is designed as a largerbolt-on hatch assembly which covers the plurality of legs of the exhaustafter-treatment system, while the second smaller roof panel 1506 isdesigned as a smaller bolt-on hatch assembly positioned above theturbocharger location, with the horn system mounted to it. This designallows for relatively good service access. Additionally, in theembodiment shown in FIG. 15, the hinged system allows access to the sidelegs of the exhaust after-treatment system while keeping the middle legcovered.

Packaging the horn system within the Plate L clearance profile whilealso finding a suitable location for the horn system above the enginecab roof can pose design challenges. Additionally, if any changes aremade to the horn system, or its location, Federal RailroadAdministration (FRA) regulations require the changes to be tested perFRA rules. FIGS. 16A-B show two different horn system configurations(1600 and 1650, respectively) that have been designed taking thesechallenges into account. As such, each horn system 1600, 1650 mayinclude one or more horns positioned above the engine within locomotiveengine cab 1606, at a front end 1604 of the engine cab 1606 between theafter-treatment system and a front wall of the cab, an open end 1608 ofat least one horn facing towards the center of the engine cab 1606. Thefirst embodiment 1600 (FIG. 16A) depicts a single 5-chime horn 1601while the second embodiment 1650 (FIG. 16B) depicts a split horn 1602including two horns, a first horn with a 3-chime configuration 1610 anda second horn with a 2-chime configuration 1612.

As elaborated previously with reference to FIG. 1, the SCR system of theexhaust after-treatment system may use a reductant, e.g., diesel exhaustfluid (DEF; referring to a 32.5% solution of urea in water), for thereduction of exhaust NOx species. In the example embodiment of FIG. 1,in a urea-based (e.g., DEF) system, the urea tank for storing urea maybe sized such that the frequency of refilling urea in the urea tankmatches refueling of the locomotive engine fuel tank. The urea tank anddelivery system may also be designed to allow for reasonableserviceability of the engine, alternator, and radiator cab with minimalmodification/redesign of existing locomotive hardware.

With regard to the location of the urea (e.g., DEF) or other reductantstorage tank, various configurations are contemplated that take intoaccount the design constraints. These configurations include, forexample, carving the urea tank out of the existing fuel tank for theengine, installing the urea tank on the locomotive walkway as a raisedwalkway, and installing the urea tank in the radiator cab.

FIGS. 17A-17F show various embodiments where a urea (e.g., DEF) or otherreductant storage tank 1700 is configured as a raised walkway 1702 on alocomotive or other vehicle 1704. These designs may reduce sloshing anddead-volume issues while maintaining an ergonomic step progression downa side of the locomotive or other vehicle. FIG. 17A shows a tank 1700and engine 210 in isolation, for reference or comparison purposes. Asindicated, the tank 1700 includes an inlet for receiving DEF or otherurea (or other reductant), and is connected to the engine system (e.g.,an emissions system portion of the engine system) for delivering DEF orother urea. FIG. 17B is a perspective view of a first embodiment of atank 1700 configured as a raised walkway 1702. The tank 1700 extendsfrom a battery box or other vehicle structure portion 1706 on one sideof the vehicle (e.g., the “A” side of a locomotive), and steps down to alower deck 1710 along an operator cab, engine cab, or other cab 1712 ofthe vehicle. (In any of the embodiments, the lower deck 1710 may be thelowest walkway, with respect to a ground level, along the side of thevehicle, and/or the lower deck 1710 is a deck located at a standard deckheight of the vehicle or class of vehicles in question; see the arrow inFIG. 17D.) More specifically, the top walkway portion of the tank 1700is level with a top of the battery box or other vehicle structureportion 1706, for forming a top continuous portion of the raised walkway1702. The tank 1700 extends from the vehicle structure portion 1706along the cab 1712, and terminates at a step portion 1707 of the tank,which has a reduced height in comparison with the top of the tank andvehicle structure portion. (More specifically, with respect to the lowerdeck 1710, the tank has two heights. The first height is equal to aheight of the vehicle structure portion 1706. The second height, of thestep portion 1707, is smaller than the first height, but above the lowerdeck.) The step portion 1707 provides a transition for human operatorsto traverse from the top of the tank and vehicle structure portion tothe lower deck 1710. In this way, the urea tank forms part of a platformof a walkway to a side of the vehicle, on an exterior of the operatorcab.

FIG. 17C is a perspective view of a second embodiment of a tank 1700configured as a raised walkway 1702. The tank 1700 abuts a battery boxor other vehicle structure portion 1706, extends along one side of thevehicle (e.g., the “A” side of a locomotive), and terminates proximate arear portion of the vehicle. The tank 1700 is a rectangularparallelepiped (e.g., in effect encompasses six rectangular or squarefaces), and has a height, with respect to the lower deck 1710, that isless than a height of the vehicle structure portion 1706 (with respectto the lower deck 1710). Thus, the whole tank 1700 acts as a steptransition between the top surface of the vehicle structure portion 1706and the lower deck 1710.

FIG. 17D is a perspective view of a third embodiment of a tank 1700configured as a raised walkway 1702. This embodiment is similar to theembodiment in FIG. 17B, but illustrates that (i) the tank 1700 can beprovided in different lengths, and (ii) that the positioning/length ofthe vehicle structure portion 1706 (which the tank 1700 abuts) can varyfrom vehicle to vehicle.

FIG. 17E is a perspective view of a fourth embodiment of a tank 1700configured as a raised walkway 1702. This embodiment is similar to theembodiment in FIG. 17C, but illustrates that (i) the tank 1700 can beprovided in different lengths, and (ii) other structural elements 1709of the vehicle, at the same height as the tank, may be interposedbetween the tank and the vehicle structure portion 1706.

FIG. 17F is a perspective view of a fifth embodiment of a tank 1700configured as a raised walkway 1702. This embodiment is similar to theembodiment in FIGS. 17B and 17D, but illustrates that the step portion1707 can be provided in different lengths.

In any of the embodiments set forth herein, for being configured as araised walkway, the tank 1700 may have one or more of the followingfeatures: (i) top surfaces configured as walkway surfaces, e.g.,anti-skid/slip surfaces; (ii) the tank structure (e.g., top/bottom/sidewalls and any internal supports) is configured to both hold urea and tosupport the weight of plural human operators; and/or (iii) the tankstructure comprises structural elements for supporting the weight ofplural human operators, but those same structural elements are not usedfor holding urea, and the tank further includes an interior member thatholds urea but does not act for walkway support (e.g., the tankcomprises an external structure and an internal vessel; the externalstructure forms part of the walkway for supporting human operators; theinternal vessel holds urea but does not bear or support weight presentupon the walkway). Additionally, the tank may be installed in a singlesided configuration, meaning the only urea tank 1700 in the vehicle ispositioned on one side of the vehicle (the sides being defined as leftor right of a longitudinal axis of the vehicle).

Multiple urea heating systems may be included for freeze-preventionduring locomotive use. In one embodiment, the freeze prevention systemmay include a first resistive heater (e.g., submersible resistiveheater) that can deliver 1000-1200 W at 74V (DC) from the locomotivebus. The freeze prevention system may enable the urea to be kept in aliquid state even when ambient temperatures dip to −40° C. Urea thawingmay be needed in the case of a locomotive shutdown, such as when thelocomotive has been shutdown for a number of days while being exposed totemperatures below −10° C. In one embodiment, to address the thawing, asecond resistive heater (e.g., submersible resistive heater) may beincluded that can provide 6000-10,000 W at 240V (AC) from a way-sidepower source (such as, a wayside locomotive repair shop). In oneexample, the second submersible heater can completely thaw a full tankof urea in approximately 24 hours.

In one embodiment, only a fraction of the urea flow (or flow of otherreductant), delivered to the exhaust after-treatment system from theurea tank by the urea injectors of the urea delivery system, is injectedinto the after-treatment system for mixing, hydrolysis, and subsequentNOx reduction. In this embodiment, the remaining un-injected fraction ofthe urea flow is used to cool the urea injectors before being returnedto the urea tank. Such an embodiment may include urea delivery lines,urea return lines, urea injectors, urea transfer pumps, filters, andheaters. The urea delivery system according to such an embodiment may beselected based on one or more factors including delivery of urea atsufficient flow and pressure for the desired application, volumerequirement that is less than the available packaging volume, and anability to interact with the urea control system equivalently to currentsystems (such as with a single pump and a single injector system).

In alternate embodiments, the urea (or other reductant) delivery systemmay include a single pump with an accumulator system, or a multi-pumpsystem having multiple pumps. The single pump system utilizes anaccumulator to hold a volume of pressurized urea available for injectionfrom all six injectors as needed. The accumulator helps to moderatepressure oscillations from the single pump that are more pronounced thanthose experienced on a system utilizing multiple pumps. In comparison,the multi-pump system utilizes individual pumps for each leg (exhaustafter-treatment unit) of the exhaust after treatment system with apotential requirement for a (low-pressure) supply pump to assist inpriming. An example multi-pump urea delivery system is shown in FIG. 18.In FIG. 18, a multi-pump reductant delivery system 1800 includes areductant storage tank 1802, a low-pressure feed/supply pump section1804 (boost pump section), and a high-pressure pump section 1806 foreach leg/unit. (Low pressure and high pressure are relative, meaning thelow-pressure pump is a lower pressure than the high-pressure pump.)

As previously mentioned, in some embodiments, the exhaustafter-treatment system further includes a delivery system including adelivery line and a delivery pump for receiving reductant from thereductant storage tank, as shown in FIG. 19. In one example, the ureadelivery lines may be sized to about 1.5″/˜3.8 cm outer diameter each(with a diameter of ˜3″/˜7.6 cm in a bundle). As shown in FIG. 19, atleast a portion of the urea delivery line 1904 of urea delivery system1902 is mounted along engine block 1908 and along the longitudinal axis1910 of after-treatment system 1901. By mounting urea delivery lines1904 on exhaust after-treatment system 1901, engine maintenancedisturbances are avoided, as well as avoiding exposing the urea tohigher temperatures on the turbocharger end 1914 of engine 1912.

In this way, by configuring an exhaust after-treatment system with aplurality of leg and sub-legs (exhaust after-treatment units), theafter-treatment system can be designed to be accommodated within avariety of vehicles. Further, by using cylindrical substrates for eachleg, it is possible that further compaction may be achieved withoutreducing the number of after-treatment components in each leg.

As described herein, certain embodiments of an emissions control systeminclude one or more diesel particulate filters 106 (“DPF”).Alternatively, in any of the embodiments set forth herein, differenttypes of filters may be used (such as flow-thru filters), or it may bethe case that no filter is used.

According to one aspect, “distinct” means that exhaust that travelsthrough one passage does not travel through the others (when thepassages are arrayed in parallel) and/or that common structure is notshared for defining the passages.

According to one aspect of the invention, the exhaust after-treatmentsystem includes plural exhaust after-treatment units (the units may bearranged for functional operation in parallel), where each unit definesan exhaust flow passage and includes (within or otherwise associatedwith the passage) a respective plurality of different types of exhaustafter-treatment component, e.g., each unit may include a filter, andanother type of exhaust after-treatment component different than afilter. That is, a first unit includes a first set of exhaustafter-treatment components having a first exhaust after-treatmentcomponent and a second exhaust after-treatment component, the first andsecond components being different types of components from one another;a second unit includes a second set of exhaust after-treatmentcomponents having a third exhaust after-treatment component and a fourthexhaust after-treatment component, the third and fourth components beingdifferent types of components from one another; etc. The first set maybe the same as the second set, or different. (That is, if the first unitincludes a first component “A” and a first component “B,” with A and Bbeing different types of components from one another, the second unitmay include a second component A and a second component B, or the secondunit may include A (or B) and a component “C” (of a different type thanA or B), or the second unit may include components C and “D,” C being adifferent type of component than D.)

Thus, in an embodiment, an emissions control system comprises an exhaustafter-treatment system and a control module. The exhaust after-treatmentsystem comprises plural exhaust treatment units, functionally arrangedin parallel (that is, parallel in regards to function, not necessarilythat the units are geometrically parallel, although that is an option),where each unit defines an exhaust flow passage and includes (within orotherwise associated with the passage) a respective plurality ofdifferent types of exhaust after-treatment components. Inputs of theexhaust treatment units are connected to an exhaust outlet of an engine,for receiving an exhaust stream from the engine. The control module isin communication with the exhaust after-treatment system for controllingat least one of the different types of exhaust after-treatmentcomponents in the exhaust treatment units, e.g., for controllingrespective injection of an amount of reductant into a portion of theexhaust stream flowing through each of exhaust treatment units.

FIG. 20 illustrates an embodiment of such an emissions control system.Here, an emissions control system 2000 comprises an exhaustafter-treatment system 2002 and a control module 2004. The exhaustafter-treatment system 2002 comprises plural exhaust treatment units2006 a, 2006 b, 2006 c, functionally arranged in parallel, where eachunit 2006 a -2006 c defines a respective exhaust flow passage 2008 a,2008 b, 2008 c and includes (within or otherwise associated with thepassage) a respective plurality of different types of exhaustafter-treatment components 2010. (For clarity of illustration, theexhaust after-treatment components are collectively labeled 2010;however, as described herein, this does not mean the components arenecessarily the same. Instead, for a given exhaust treatment unit, thecomponents of the exhaust treatment unit are different from oneanother.) Inputs 2012 of the exhaust treatment units are connected to anexhaust outlet 2014 of an engine 2016, for receiving an exhaust stream2018 from the engine. The control module 2004 is in communication withthe exhaust after-treatment system 2002 for controlling at least one ofthe different types of exhaust after-treatment components 2010 in theexhaust treatment units, e.g., for controlling respective injection ofan amount of reductant into a portion of the exhaust stream flowingthrough each of exhaust treatment units. Although FIG. 20 shows threeexhaust treatment units, the system may include two, or more than three,exhaust treatment units. Additionally, although FIG. 20 shows threeexhaust after-treatment components associated with each exhausttreatment unit, each unit may have two or more than three exhaustafter-treatment components.

The other figures and associated description herein are applicable, invarious embodiments, to the system shown in FIG. 20. For example, eachexhaust treatment unit 2006 a, 2006 b, 2006 c may include a PM reductionsystem 103 and/or an SCR system 107 as shown in FIG. 1.

Another embodiment relates to an emissions control system comprising acontrol module and an exhaust after-treatment system. The exhaustafter-treatment system includes a plurality of exhaust after-treatmentunits (functionally arranged in parallel or otherwise). Each exhaustafter-treatment unit respectively includes at least one substrate, aparticulate matter reduction system, and a selective catalytic reductionsystem. The at least one substrate defines an exhaust flow passage; aninput of the exhaust flow passage is connectable to an exhaust outlet ofan engine (such as an engine in a locomotive or other rail vehicle). Theparticulate matter reduction system has a diesel particulate filter anda diesel oxidation catalyst upstream of the diesel particulate filter.The selective catalytic reduction system is downstream of the dieselparticulate filter. The selective catalytic reduction system has areductant injector (with an injector output in the exhaust flow passageat an injection site), a selective catalytic reduction catalystdownstream of the injection site, and an ammonia slip catalystdownstream of the selective catalytic reduction catalyst. The controlmodule is configured to communicate with the exhaust after-treatmentsystem for controlling each reductant injector for injection ofreductant in the exhaust flow passage at the injection site. In anotherembodiment of the locomotive, each after-treatment unit furthercomprises a regeneration device for regenerating the diesel particulatefilter; the regeneration device may include a burner.

FIG. 22 illustrates an example of an emissions control system 2200 asdescribed immediately above. The emissions control system 2200 includesa control module 2202 and an exhaust after-treatment system 2204. Theexhaust after-treatment system 2204 includes a plurality of exhaustafter-treatment units 2206 a, 2206 b; in an embodiment, as shown in FIG.22, the units are shown functionally arranged in parallel. (Two units2206 a, 2206 b are shown in FIG. 21; however, the system may includemore than two such units.) Each exhaust after-treatment unit 2206 a,2206 b respectively includes at least one substrate 2208, a particulatematter reduction system 2210, and a selective catalytic reduction system2212. The at least one substrate 2208 defines an exhaust flow passage2214; an input 2216 of the exhaust flow passage is connectable to anexhaust outlet of an engine 2218 (such as an engine in a locomotive orother rail vehicle). The particulate matter reduction system 2210 has adiesel particulate filter 2220 and a diesel oxidation catalyst 2222upstream of the diesel particulate filter. The selective catalyticreduction system 2212 is downstream of the diesel particulate filter2220. The selective catalytic reduction system 2212 has a reductantinjector 2224 (with an injector output 2226 in the exhaust flow passageat an injection site 2228), a selective catalytic reduction catalyst2230 downstream of the injection site, and an ammonia slip catalyst 2232downstream of the selective catalytic reduction catalyst. The controlmodule 2202 is configured to communicate with the exhaustafter-treatment system for controlling each reductant injector forinjection of reductant in the exhaust flow passage at the injectionsite. In another embodiment of the locomotive, each after-treatment unit2206 a, 2206 b further comprises a regeneration device 2234 forregenerating the diesel particulate filter; the regeneration device mayinclude a burner. (In FIG. 22 the sub-elements of the after-treatmentunit 2206 b are not numbered, for clarity of illustration, but, in anembodiment, are the same as those of unit 2206 a.)

Another embodiment relates to a method of operating an exhaustafter-treatment system. The method includes a step of dividing anexhaust stream from an engine into a plurality of exhaust sub-streams.The method additionally includes a step of respectively routing theplurality of sub-streams through a plurality of exhaust after-treatmentunits. The method additionally includes, in each exhaust after-treatmentunit, a step of treating the exhaust sub-stream routed through theexhaust after-treatment unit using a first exhaust after-treatmentcomponent of the exhaust after-treatment unit.

In another embodiment of the method, the first exhaust after-treatmentcomponent comprises a reductant injector. The method further includes astep of injecting reductant into each of the plurality of sub-streams.In this manner, the exhaust sub-streams are treated through chemicalalteration of a predetermined chemical component of the exhaust streamin response to the injected reductant.

In another embodiment, the method further includes a step of, in eachexhaust after-treatment unit, filtering the exhaust sub-stream routedthrough the exhaust after-treatment unit prior to the exhaust sub-streamencountering the injected reductant. The filtration step may beperformed using a filter, and the method may further include a step ofregenerating the filter with a burner.

Another embodiment relates to an emissions control system having atransition section and an exhaust after-treatment system. The transitionsection is attachable to an exhaust outlet of an engine and configuredto divide an exhaust stream exiting the exhaust outlet into pluralexhaust sub-streams. The exhaust after-treatment system has a pluralityof exhaust after-treatment units through which the plural exhaustsub-streams can be directed to respectively flow. Each exhaustafter-treatment unit has at least one exhaust after-treatment componentfor treating a portion of the exhaust sub-stream flowing through theunit. Portions of FIGS. 1-22 are applicable to such an emissions controlsystem. FIG. 23 shows another embodiment. Here, an emissions controlsystem 2300 includes a transition section 2302 and an exhaustafter-treatment system 2304. The transition section 2302 is attachableto an exhaust outlet 2306 of an engine 2308 and configured to divide anexhaust stream 2310 exiting the exhaust outlet into plural exhaustsub-streams 2312. The exhaust after-treatment system 2304 has aplurality of exhaust after-treatment units 2314 through which the pluralexhaust sub-streams can be directed to respectively flow. Each exhaustafter-treatment unit 2314 has at least one exhaust after-treatmentcomponent 2316 for treating a portion of the exhaust sub-stream flowingthrough the unit. In another embodiment, each exhaust after-treatmentunit 2314 includes a particulate matter reduction system having a dieselparticulate filter and a diesel oxidation catalyst upstream of thediesel particulate filter, and a selective catalytic reduction systemdownstream of the diesel particulate filter and having a reductantinjector with an injector output in the exhaust flow passage at aninjection site, a selective catalytic reduction catalyst downstream ofthe injection site, and an ammonia slip catalyst downstream of theselective catalytic reduction catalyst (such as shown in FIG. 1).

In another embodiment, an emissions control system includes a supportstructure and an exhaust after-treatment system. The support structureis at least partially positioned above an engine. (The engine is capableof producing an exhaust stream.) The exhaust after-treatment system hasat least one exhaust after-treatment unit through which at least aportion of the exhaust stream is directed to flow. Each exhaustafter-treatment unit has at least one exhaust after-treatment componentfor treating the portion of the exhaust stream flowing through the unit.The exhaust after-treatment unit is attached to the support structureand positioned above the engine. Portions of FIGS. 1-20 and 22-23 areapplicable to such an emissions control system. FIG. 21 shows anotherembodiment. Here, an emissions control system 2100 includes a supportstructure 2102 and an exhaust after-treatment system 2104. The supportstructure 2102 is at least partially positioned above an engine 2106.(The engine 2106 is capable of producing an exhaust stream 2108.) Theexhaust after-treatment system 2104 has at least one exhaustafter-treatment unit 2110 through which at least a portion of theexhaust stream is directed to flow. Each exhaust after-treatment unit2110 has at least one exhaust after-treatment component 2112 fortreating the portion of the exhaust stream flowing through the unit.Each of the at least one exhaust after-treatment unit is attached to thesupport structure 2102 and positioned above the engine.

In an embodiment, other parts of the system 2100 as shown in FIG. 21 areas described with respect to FIG. 20.

In another embodiment of an emissions control system, the exhaustafter-treatment system 2104 includes a plurality of exhaustafter-treatment units 2110. The system 2100 further comprises atransition section attached to an exhaust outlet of the engine thatdivides the exhaust stream into plural exhaust sub-streams respectivelydirected through the plurality of exhaust after-treatment units. (SeeFIG. 23 and related description as an example.) The plurality of exhaustafter-treatment units are attached to the support structure andpositioned above the engine.

In another embodiment of an emissions control system, the supportstructure 2102 is attached to the engine 2106. For example, the supportstructure 2102 may be attached to a frame, engine block, cover, or otherload-bearing portion 2114 of the engine, which is capable of bearing theweight of the support structure and exhaust treatment unit(s) withoutdamage to the engine. In an embodiment, the support structure 2102 isattached to one or more parts of the engine that are capable of bearingat least 5000 pounds/˜2250 kg without damage, which is a typical weightfor relatively large sized components (support structure, exhaustafter-treatment units, transition section) used in conjunction with alocomotive or similar diesel engine. This embodiment is applicable to anexhaust after-treatment system with one exhaust after-treatment unit(leg) or with plural exhaust after-treatment units.

In another embodiment of an emissions control system, where the supportstructure 2102 is attached to the engine 2106, the support structureincludes a base and a plurality of mounting legs. The plurality ofmounting legs are respectively attached to the engine at a plurality ofdifferent mounting locations, and the base is attached to the legs(e.g., to distal ends of the legs) and positioned above the engine. Theexhaust after-treatment unit(s) is directly or indirectly attached tothe base, that is, directly connected to the base, or connected toelements that are in turn connected to the base. Examples of such anarrangement are shown in FIGS. 9A-9C.

In another embodiment of an emissions control system, the supportstructure comprises a plurality of isolators. Each exhaustafter-treatment unit is attached to one or more of the isolators abovethe engine for vibration reduction. For example, the isolators may beattached to the base, and the exhaust after-treatment unit(s) attachedto the isolators. Example isolators 915, 915 a, 915 b are shown anddescribed in FIGS. 9B-9C and related description.

The isolators may be metallic isolators, as described above.Alternatively or additionally, the plurality of isolators may includeone or more first isolators and one or more second isolators; the firstisolators and the second isolators are different types of isolators.Here, each exhaust after-treatment unit is attached to at least one ofthe first isolators and to at least one of the second isolators. Forexample, the first isolators may be a first type of metallic isolator(e.g., wire mesh isolators) and the second isolators may be a second,different type of metallic isolator (e.g., cable-mounted isolators). Inanother embodiment, the first isolators are relatively stiff isolators(more resistance to movement), and the second isolators are relativelysoft isolators (less resistance to movement). In another embodiment, thefirst isolators are adapted for accommodating a buff load of the exhaustafter-treatment system, and the second isolators are adapted foraccommodating thermal expansion of the exhaust after-treatment system.For example, depending on the particular component used, relativelystiff isolators (e.g., wire mesh isolators) may be better adapted toaccommodating a buff load, and relatively soft isolators (e.g.,cable-mounted isolators) may be better adapted to accommodating thermalexpansion.

Example isolator configurations are further explained in regards toFIGS. 9A-9C and related description. FIGS. 24 and 25 additionallyillustrate two embodiments of a cable-mounted isolator configuration. InFIG. 24, a cable-mounted isolator 2400 (shown in side elevation view) isattached to the base 2402 of a support structure (such as mountable toand/or above an engine). In turn, an exhaust after-treatment unit 2404is attached to the cable-mounted isolator 2400. In this manner, theexhaust after-treatment unit 2404 is attached to and supported by thebase 2402, but the amount of vibration transferred from the base to theunit (such as generated by operation of the engine) is reduced, andthermal expansion is accommodated. In FIG. 25, a cable-mounted isolator2500 (shown in perspective view) is attached to a support member 2502,which is in turn attached to the base 2504 of a support structure. Amounting bracket 2506 is attached to the cable-mounted isolator 2500.The mounting bracket 2506 supports, and/or is part of, an exhaustafter-treatment unit 2508. FIG. 26 additionally illustrates aconfiguration with a wire mesh isolator. Here, a wire mesh isolator 2600(shown in side elevation view) is attached to the base 2602 of a supportstructure (such as mountable to and/or above an engine). In turn, anexhaust after-treatment unit 2604 is attached to the wire mesh isolator2600. The wire mesh isolator includes a wire mesh element thatinterconnects and/or buffers two end connector elements, e.g., the wiremesh element is sandwiched between and attached to the end connectorelements for conferring a degree of movement there between.

In another embodiment, an emissions control system includes a supportstructure and an exhaust after-treatment system. The support structureincludes a base, a plurality of mounting legs, and a plurality ofisolators. The mounting legs are respectively attached to an engine at aplurality of different mounting locations. The base is attached to thelegs and positioned above the engine. The isolators are attached to thebase. The exhaust after-treatment system includes a plurality of exhaustafter-treatment units through which an exhaust stream of the engine isdirected to flow. Each exhaust after-treatment unit has at least oneexhaust after-treatment component for treating a portion of the exhauststream flowing through the unit. The plurality of isolators includesplural first isolators and plural second isolators; the first isolatorsand the second isolators are different types of isolators. Each of theexhaust after-treatment units is attached to at least one of the firstisolators and to at least one of the second isolators. For example, eachexhaust after-treatment unit may be attached to the base by way of (i)at least one wire mesh isolator or other relatively stiff isolator and(ii) at least one cable-mounted isolator or other relatively softisolator. As another example, each exhaust after-treatment unit may beattached to the base by way of only one wire mesh isolator or otherrelatively stiff isolator and plural cable-mounted isolators or otherrelatively soft isolators.

With reference to FIG. 27, another embodiment relates to an emissionscontrol system 2700. The system 2700 includes a support structure 2702.The support structure 2702 includes a plurality of mounting legs 2704, abase 2706 attached to the legs (e.g., attached to distal ends of thelegs), and a plurality of isolators 2708 a, 2708 b for attachment to thebase 2706. The mounting legs 2704 are spaced apart for mounting to anengine 2710 at a plurality of different mounting locations 2712 andpositioning of the base above the engine. The plurality of isolators2708 a, 2708 b comprises plural first isolators 2708 a and plural secondisolators 2708 b; the first isolators and the second isolators aredifferent types of isolators. The base 2706 includes an array ofattachment points 2714 for the plurality of isolators, for each of aplurality of exhaust after-treatment units 2716 to be attached to thebase by way of at least one of the first isolators 2708 a and at leastone of the second isolators 2708 b.

Another embodiment relates to a rail vehicle (e.g., locomotive) system.The rail vehicle system includes an engine cab defined by a roofassembly and side walls, an engine positioned in the engine cab suchthat a longitudinal axis of the engine is aligned in parallel to alength of the engine cab, and an exhaust after-treatment system. Theexhaust after-treatment system defines a plurality of distinct exhaustflow passages. Each of the plurality of exhaust flow passages isconfigured to receive at least some exhaust gas from an exhaust manifoldof the engine. The exhaust after-treatment system is mounted above theengine within a space defined by a top surface of the engine exhaustmanifold, the roof assembly, and the side walls of the engine cab, suchthat a longitudinal axis of the exhaust after-treatment system isaligned at least generally parallel to the longitudinal axis of theengine.

In another embodiment of the rail vehicle system, the plurality ofdistinct exhaust flow passages are aligned at least generally parallelto each other, and at least generally parallel to the longitudinal axisof the exhaust after-treatment system.

In another embodiment of the rail vehicle system, the system furtherincludes a support structure attached to the engine. The supportstructure comprises a base and a plurality of mounting legs. Themounting legs are respectively attached to the engine at a plurality ofdifferent mounting locations. The base is attached to the legs andpositioned above the engine. At least one of the exhaust flow passagesof the exhaust after-treatment system is attached to the base andpositioned above the engine.

In another embodiment of the rail vehicle system, the plurality ofmounting locations include at least some locations on an engine block ofthe engine and at least some locations on a front end of the engine.

In another embodiment of the rail vehicle system, the roof assemblyincludes a plurality of roof panels that are hingedly-attached to(hinged to) a side wall of the engine cab such that the exhaustafter-treatment system is accessible through at least one of theplurality of hingedly-attached roof panels.

In another embodiment of the rail vehicle system, the roof panels are ofsubstantially equal dimensions. Alternatively, the plurality of roofpanels includes a first larger panel and a second smaller panel.

In another embodiment, the rail vehicle system additionally includes ahorn system with one or more horns positioned above the engine withinthe engine cab, at a front end of the engine cab between the exhaustafter-treatment system and a front wall of the cab. An open end of atleast one horn faces towards a center of the engine cab.

Other details of the rail vehicle system described immediately above canbe referenced from the figures and accompanying description.

Another embodiment relates to a vehicle system. The vehicle systemincludes a walkway and a tank. The walkway has a support frame. Thesupport frame defines a walkway surface and is configured to accommodateat least the weight of an average human adult (at least 90 kg). The tankis positioned within an interior of the support frame, and is configuredto hold liquid (e.g., urea/DEF or other reductant). Further informationrelating to the vehicle system, in various embodiments, can be found inFIGS. 12-17F and related description; see also FIG. 28 and relateddescription.

In another embodiment of the vehicle system, the walkway surface isplanar and has a length and a width, the length being longer than thewidth, and the width being at least wide enough to accommodate theaverage human adult walking along the walkway (at least 1″/0.3 m wide).Further information relating to the vehicle system of this embodimentcan be found in FIGS. 17A-17F and related description.

In another embodiment of the vehicle system, the support frame defines astep in the walkway surface, the step transitioning from a first levelof the walkway to a second level of the walkway. Further informationrelating to the vehicle system of this embodiment can be found in FIGS.17B, 17D, and 17F and related description.

In another embodiment of the vehicle system, the walkway is a sidewalkway of the rail vehicle. The side walkway extends from towards afront of the rail vehicle to towards a rear of the rail vehicle, along aside of the rail vehicle. “Towards a front” means starting within thefront half of the vehicle, and “towards a rear” means extendingrearwards. Further information relating to the vehicle system of thisembodiment can be found in FIGS. 17A-17F and related description.

With reference to FIG. 28, another embodiment relates to a vehiclesystem 2800. The vehicle system 2800 includes a walkway 2802 and a tank2804. The walkway has a support frame 2806. The support frame 2806defines a walkway surface 2808 and is configured to accommodate at leastthe weight of an average human adult. The tank 2804 is positioned withinan interior of the support frame, and is configured to hold liquid 2810(e.g., urea or other reductant). The tank 2804 is an interior surface2812 of the support frame. The support frame thereby both supports (atleast) an average human adult and defines a volume of the tank.

In another embodiment of a vehicle system, the system further includes afirst resistive heater (e.g., submersible resistive heater) in thermalconnection with the tank and configured to be driven by an electricalbus of a vehicle for heating the liquid (e.g., urea or other reductant)at a first heat output (e.g., wattage). In another embodiment, thevehicle system further includes a second resistive heater (e.g.,submersible resistive heater) in thermal connection with the tank andconfigured to be driven by an off-vehicle electrical power source forheating the liquid (e.g., urea or other reductant) at a second heatoutput. The second heat output is greater than the first heat output.Either embodiment (first and/or second resistive heater) is applicablefor use in conjunction with any of the other embodiments set forthherein. As one example, however, with reference to FIG. 28, a firstresistive heater 2814 is in thermal connection with the tank andconfigured to be driven by an electrical bus 2816 of a vehicle forheating the liquid (e.g., urea or other reductant) at a first heatoutput (e.g., wattage). A second resistive heater 2818 is in thermalconnection with the tank and configured to be driven by an off-vehicleelectrical power source 2820 for heating the liquid (e.g., urea or otherreductant) at a second heat output. As noted, the second heat output maybe greater than the first heat output. Other information relating tothese embodiments can be found in the sections above relating to theurea heating systems.

Another embodiment relates to a rail vehicle. The rail vehicle comprisesa walkway and a tank. The walkway has a support frame. The support framedefines a walkway surface and is configured to accommodate at least theweight of an average human adult. The tank is positioned within aninterior of the support frame, and is configured to hold liquid (e.g.,urea or other reductant). In an embodiment, the tank is fluidly attachedto an emissions control system of the rail vehicle for delivering theurea or other reductant to the emissions control system. In anembodiment, the tank is the only tank in the rail vehicle for holdingurea or other reductant.

In another embodiment, a vehicle system includes an engine cab, anengine, and an exhaust after-treatment system. The engine cab is definedby a roof assembly and side walls. The engine is positioned in theengine cab such that a longitudinal axis of the engine is aligned inparallel to a length of the engine cab. The exhaust after-treatmentsystem defines at least one exhaust flow passage. The at least oneexhaust flow passage is configured to receive exhaust gas from anexhaust manifold of the engine. The exhaust after-treatment system ismounted such that a longitudinal axis of the exhaust after-treatmentsystem is aligned at least generally parallel to the longitudinal axisof the engine. The exhaust after-treatment system includes a reductantstorage tank, and, for each exhaust flow passage, a respective reductantinjector configured to inject a reductant from the reductant storagetank into an injection site in the exhaust flow passage. The reductantstorage tank forms at least part of an exterior operator walkwaypositioned on a side of the engine cab.

In another embodiment, the exhaust after-treatment system furtherincludes a delivery system with a delivery line and a delivery pump forreceiving reductant from the reductant storage tank. At least a portionof the delivery line is mounted along an engine block and along thelongitudinal axis of the exhaust after-treatment system.

Another embodiment relates to an emissions control system. The emissionscontrol system includes a reductant (e.g., urea) delivery system fordelivering reductant to a reductant injector. The reductant deliverysystem is configured to control delivery of the reductant to thereductant injector such that a flow rate of the delivered reductant isgreater than a rate of reductant injected by the reductant injector. Thereductant delivery system includes a flow path for routing anun-injected portion of the delivered reductant to cool the reductantinjector prior to returning to a reductant storage tank.

In another embodiment, a vehicle system includes an engine cab, anengine, and an exhaust after-treatment system. The engine cab is definedby a roof assembly and side walls. The engine is positioned in theengine cab such that a longitudinal axis of the engine is aligned inparallel to a length of the engine cab. The exhaust after-treatmentsystem defines at least one exhaust flow passage. The at least oneexhaust flow passage is configured to receive exhaust gas from anexhaust manifold of the engine. The exhaust after-treatment system ismounted such that a longitudinal axis of the exhaust after-treatmentsystem is aligned at least generally parallel to the longitudinal axisof the engine. The exhaust after-treatment system includes a reductantstorage tank, and, for each exhaust flow passage, a respective reductantinjector configured to inject a reductant from the reductant storagetank into an injection site in the exhaust flow passage. The exhaustafter-treatment system also includes a reductant (e.g., urea) deliverysystem for delivering reductant to the reductant injector(s). Thereductant delivery system is configured to control delivery of thereductant to the reductant injectors such that a flow rate of thedelivered reductant is greater than a rate of reductant injected by thereductant injectors. The reductant delivery system includes a flow pathfor routing an un-injected portion of the delivered reductant to coolthe reductant injectors prior to returning to a reductant storage tank.

Another embodiment relates to an emissions control system. The emissionscontrol system includes an exhaust after-treatment system having pluralreductant injectors and a reductant delivery system for deliveringreductant to the plural reductant injectors. The reductant deliverysystem comprises one of: a single pump and an accumulator system, wherethe single pump is configured to pump the reductant to the accumulatorsystem and the accumulator system is configured to hold pressurizedreductant available for injection by the plural reductant injectors asneeded; or plural pumps for respectively delivering the reductant to theplural reductant injectors.

In another embodiment, the reductant delivery system further includes areductant supply line for routing reductant from a reductant tank to theinjectors. At least part of the reductant supply line is routed along anengine block of an engine whose exhaust is to be treated by the exhaustafter-treatment system and at least part of the reductant supply line isrouted along the exhaust after-treatment system.

Another embodiment relates to an emissions control system, comprising acontrol module and an exhaust after-treatment system with a plurality ofexhaust after-treatment units, wherein. Each exhaust after-treatmentunit respectively comprises: at least one substrate defining an exhaustflow passage, where an input of the exhaust flow passage is connectableto an exhaust outlet of an engine; a particulate matter reduction systemhaving a diesel particulate filter and a diesel oxidation catalystupstream of the diesel particulate filter; and a selective catalyticreduction system downstream of the diesel particulate filter and havinga reductant injector with an injector output in the exhaust flow passageat an injection site, a selective catalytic reduction catalystdownstream of the injection site, and an ammonia slip catalystdownstream of the selective catalytic reduction catalyst. The controlmodule is configured to communicate with the exhaust after-treatmentsystem for controlling each reductant injector for injection ofreductant in the exhaust flow passage at the injection site. In anotherembodiment, each exhaust after-treatment unit further comprises aregeneration device for regenerating the diesel particulate filter, theregeneration device including a burner.

Another embodiment relates to a method of operating an exhaustafter-treatment system. The method includes dividing an exhaust streamfrom an engine into a plurality of exhaust sub-streams; respectivelyrouting the plurality of sub-streams through a plurality of exhaustafter-treatment units; and in each exhaust after-treatment unit,treating the exhaust sub-stream routed through the exhaustafter-treatment unit using a first exhaust after-treatment component ofthe exhaust after-treatment unit. In another embodiment, the firstexhaust after-treatment component comprises a reductant injector, andthe method further comprises injecting reductant into each of theplurality of sub-streams, whereby the exhaust sub-streams are treatedthrough chemical alteration of a determined chemical component of theexhaust stream in response to the injected reductant. In anotherembodiment, the method further comprises, in each exhaustafter-treatment unit, filtering the exhaust sub-stream routed throughthe exhaust after-treatment unit prior to the exhaust sub-streamencountering the injected reductant. In another embodiment, the exhaustsub-stream is filtered using a filter, and the method further comprisesregenerating the filter with a burner.

Another embodiment relates to an emissions control system. The systemcomprises a transition section attachable to an exhaust outlet of anengine and configured to divide an exhaust stream exiting the exhaustoutlet into plural exhaust sub-streams, and an exhaust after-treatmentsystem having a plurality of exhaust after-treatment units through whichthe plural exhaust sub-streams can be directed to respectively flow.Each exhaust after-treatment unit has at least one exhaustafter-treatment component for treating a portion of the exhaustsub-stream flowing through the unit. In another embodiment, each exhaustafter-treatment unit includes a particulate matter reduction systemhaving a diesel particulate filter and a diesel oxidation catalystupstream of the diesel particulate filter, and a selective catalyticreduction system downstream of the diesel particulate filter and havinga reductant injector with an injector output in the exhaust flow passageat an injection site, a selective catalytic reduction catalystdownstream of the injection site, and an ammonia slip catalystdownstream of the selective catalytic reduction catalyst.

Another embodiment relates to an emissions control system. The systemincludes a support structure comprising a base, a plurality of mountinglegs, and a plurality of isolators, the plurality of mounting legsrespectively attached to an engine at a plurality of different mountinglocations, and the base attached to the legs and positioned above theengine, wherein the isolators are attached to the base. The system alsoincludes an exhaust after-treatment system having a plurality of exhaustafter-treatment units through which an exhaust stream of the engine isdirected to flow, each exhaust after-treatment unit having at least oneexhaust after-treatment component for treating a portion of the exhauststream flowing through the unit. The plurality of isolators comprisesplural first isolators and plural second isolators, the first isolatorsand the second isolators being different types of isolators. Each of theexhaust after-treatment units is attached to at least one of the firstisolators and to at least one of the second isolators. In anotherembodiment, the first isolators are wire mesh isolators, and the secondisolators are cable-mounted isolators.

Another embodiment relates to an emissions control system. The systemincludes a support structure comprising a plurality of mounting legs, abase attached to the legs, and a plurality of isolators for attachmentto the base, the plurality of mounting legs spaced apart for mounting toan engine at a plurality of different mounting locations and positioningof the base above the engine. The plurality of isolators comprisesplural first isolators and plural second isolators, the first isolatorsand the second isolators being different types of isolators. The baseincludes an array of attachment points for the plurality of isolators,for each of a plurality of exhaust after-treatment units to be attachedto the base by way of at least one of the first isolators and at leastone of the second isolators.

Another embodiment relates to a rail vehicle system. The system includesan engine cab defined by a roof assembly and side walls, an enginepositioned in the engine cab such that a longitudinal axis of the engineis aligned in parallel to a length of the engine cab, and an exhaustafter-treatment system defining a plurality of distinct exhaust flowpassages. Each of the plurality of exhaust flow passages is configuredto receive at least some exhaust gas from an exhaust manifold of theengine. The exhaust after-treatment system is mounted above the enginewithin a space defined by a top surface of the engine exhaust manifold,the roof assembly, and the side walls of the engine cab such that alongitudinal axis of the exhaust after-treatment system is aligned atleast generally parallel to the longitudinal axis of the engine. Inanother embodiment, the plurality of distinct exhaust flow passages arealigned at least generally parallel to each other, and at leastgenerally parallel to the longitudinal axis of the exhaustafter-treatment system. In another embodiment, the rail vehicle systemfurther comprises a support structure attached to the engine. Thesupport structure comprises a base and a plurality of mounting legs. Themounting legs are respectively attached to the engine at a plurality ofdifferent mounting locations, and the base is attached to the legs andpositioned above the engine. At least the exhaust flow passages of theexhaust after-treatment system are attached to the base and positionedabove the engine. In another embodiment, the mounting locations includeat least some locations on an engine block of the engine and at leastsome locations on a front end of the engine. In another embodiment, theroof assembly includes a plurality of roof panels hingedly-attached to aside wall of the engine cab such that the exhaust after-treatment systemis accessible through at least one of the plurality of hingedly-attachedroof panels. In another embodiment, the plurality of roof panels are ofsubstantially equal dimensions, or wherein the plurality of roof panelsincludes a first larger panel and a second smaller panel. In anotherembodiment, the rail vehicle system further comprises a horn systemincluding one or more horns positioned above the engine within theengine cab, at a front end of the engine cab between the exhaustafter-treatment system and a front wall of the cab. An open end of atleast one horn faces towards a center of the engine cab.

Another embodiment relates to a vehicle system. The vehicle systemincludes a engine cab defined by a roof assembly and side walls, anengine positioned in the engine cab such that a longitudinal axis of theengine is aligned in parallel to a length of the engine cab, and anexhaust after-treatment system defining at least one exhaust flowpassage. The at least one exhaust flow passage is configured to receiveexhaust gas from an exhaust manifold of the engine. The exhaustafter-treatment system is mounted such that a longitudinal axis of theexhaust after-treatment system is aligned at least generally parallel tothe longitudinal axis of the engine. The exhaust after-treatment systemcomprises a reductant storage tank, and, for each exhaust flow passage,a respective reductant injector configured to inject a reductant fromthe reductant storage tank into an injection site in the exhaust flowpassage. The reductant storage tank forms at least part of an exterioroperator walkway positioned on a side of the engine cab. In anotherembodiment, the exhaust after-treatment system further includes adelivery system including a delivery line and a delivery pump forreceiving reductant from the reductant storage tank. At least a portionof the delivery line is mounted along an engine block and along thelongitudinal axis of the exhaust after-treatment system.

The term “control module” refers to one or more hardware elements and/orsoftware elements configured for carrying out the indicated function ofthe control module. The hardware elements may include one or moreelectronic devices or components, such as a microcontroller or processorand related components. Software refers to a predetermined list ofnon-transient, machine readable instructions, stored in a tangiblemedium, which are used as the basis for controller hardware to carry outone or more designated functions, determined according to the contentsof the software instructions. In an embodiment, a control modulecomprises a processor/controller, related electronic components (e.g.,components for providing power to the processor/controller), andsoftware that is executed by the processor/controller to perform one ormore designated functions.

The term “generally” parallel as used herein means at or within 5degrees of parallel. The term “at least generally” parallel meansparallel or at or within 5 degrees of parallel. “Parallel (or generallyparallel)” is equivalent to stating “at least generally parallel.”“Substantially” means the stated dimension/quality but for anymanufacturing tolerances/variances. For example, “substantially equal”means equal but for manufacturing tolerances/variances.

In the specification and claims, reference will be made to a number ofterms have the following meanings. The singular forms “a”, “an”, and“the” include plural referents unless the context clearly dictatesotherwise. Approximating language, as used herein throughout thespecification and claims, may be applied to modify any quantitativerepresentation that could permissibly vary without resulting in a changein the basic function to which it is related. Accordingly, a valuemodified by a term such as “about” is not to be limited to the precisevalue specified. In some instances, the approximating language maycorrespond to the precision of an instrument for measuring the value.Similarly, “free” may be used in combination with a term, and mayinclude an insubstantial amount or immaterial structure, while stillbeing considered free of the modified term.

As used herein, the terms “may” and “may be” indicate a possibility ofan occurrence within a set of circumstances; a possession of a specifiedproperty, characteristic or function; and/or qualify another verb byexpressing one or more of an ability, capability, or possibilityassociated with the qualified verb. Accordingly, usage of “may” and “maybe” indicates that a modified term is apparently appropriate, capable,or suitable for an indicated capacity, function, or usage, while takinginto account that in some circumstances the modified term may sometimesnot be appropriate, capable, or suitable. For example, in somecircumstances an event or capacity can be expected, while in othercircumstances the event or capacity cannot occur—this distinction iscaptured by the terms “may” and “may be”.

The embodiments described herein are examples of articles, compositions,and methods having elements corresponding to the elements of theinvention recited in the claims. This written description may enablethose of ordinary skill in the art to make and use embodiments havingalternative elements that likewise correspond to the elements of theinvention recited in the claims. The scope of the invention thusincludes articles, compositions and methods that do not differ from theliteral language of the claims, and further includes other articles,compositions and methods with insubstantial differences from the literallanguage of the claims. While only certain features and embodiments havebeen illustrated and described herein, many modifications and changesmay occur to one of ordinary skill in the relevant art. The appendedclaims cover all such modifications and changes.

The invention claimed is:
 1. An emissions control system, comprising: asupport structure at least partially positioned above an engine, theengine capable of producing an exhaust stream; and an exhaustafter-treatment system having at least one exhaust after-treatment unitthrough which at least a portion of the exhaust stream is directed toflow, each exhaust after-treatment unit having at least one exhaustafter-treatment component for treating the portion of the exhaust streamflowing through the unit; wherein the at least one exhaustafter-treatment unit is attached to the support structure and positionedabove the engine and the support structure is attached to the engine forthe engine to bear the weight of the support structure and the at leastone exhaust treatment unit; wherein the support structure comprises aplurality of isolators, and each of the at least one exhaustafter-treatment unit is attached to one or more of the isolators abovethe engine for vibration reduction; wherein the support structurefurther comprises a base and a plurality of mounting legs, the pluralityof mounting legs respectively attached to the engine at a plurality ofdifferent mounting locations, the base attached to all the legs andpositioned above the engine, and the plurality of isolators mounted tothe base, and the isolators are interposed between the base and the atleast one exhaust after-treatment unit for vibration reduction of the atleast one exhaust after-treatment unit relative to the base.
 2. Theemissions control system of claim 1 wherein: the at least one exhaustafter-treatment unit of the exhaust after-treatment system comprises aplurality of exhaust after-treatment units; the system further comprisesa transition section attached to an exhaust outlet of the engine thatdivides the exhaust stream into plural exhaust sub -streams respectivelydirected through the plurality of exhaust after-treatment units; and theplurality of exhaust after-treatment units are attached to the supportstructure and positioned above the engine.
 3. The emissions controlsystem of claim 2 wherein the plurality of exhaust after-treatmentunits, the transition section, and the support structure together weighat least 2250 kg as born by the engine.
 4. The emissions control systemof claim 1 wherein the isolators are metallic isolators that areconfigured for the vibration reduction, and wherein the metallicisolators comprise at least one of wire mesh isolators or cable-mountedisolators.
 5. The emissions control system of claim 1 wherein: theplurality of isolators comprises one or more first isolators and one ormore second isolators, the first isolators and the second isolatorsbeing different types of isolators; and each of the at least one exhaustafter-treatment unit is attached to at least one of the one or morefirst isolators and to at least one of the one or more second isolators.6. The emissions control system of claim 1, wherein the engine is housedin an engine cab, and wherein the at least one exhaust after-treatmentunit is attached to the support structure and positioned above theengine such that a longitudinal axis of the at least one exhaustaftertreatment unit is at least generally parallel to a longitudinalaxis of the engine and a length of the engine cab.
 7. The emissionscontrol system of claim 1, wherein the support structure is attached toan engine block of the engine.
 8. An emissions control system,comprising: a support structure at least partially positioned above anengine, the engine capable of producing an exhaust stream, wherein thesupport structure comprises a base, a plurality of mounting legs, and aplurality of vibration reduction isolators; and an exhaustafter-treatment system having at least one exhaust after-treatment unitthrough which at least a portion of the exhaust stream is directed toflow, each exhaust after-treatment unit having at least one exhaustafter-treatment component for treating the portion of the exhaust streamflowing through the unit; wherein the plurality of mounting legs arerespectively attached at a plurality of different mounting locations toat least one of the engine or a platform on which the engine issupported, the base is attached to all the legs and positioned above theengine, the plurality of isolators are attached to the base on a side ofthe base opposite where the legs are attached, and the at least oneexhaust after-treatment unit is attached to the plurality of isolatorsabove the base such that the plurality of isolators are interposedbetween the base and the at least one exhaust after-treatment unit forvibration reduction between the base and the at least one exhaustafter-treatment unit.
 9. The emissions control system of claim 8,wherein the isolators are metallic isolators configured for thevibration reduction, and wherein the metallic isolators comprise atleast one of wire mesh isolators or cable-mounted isolators.
 10. Theemissions control system of claim 8, wherein: the at least one exhaustafter-treatment unit of the exhaust after-treatment system comprises aplurality of exhaust after-treatment units; the system further comprisesa transition section attached to an exhaust outlet of the engine thatdivides the exhaust stream into plural exhaust sub-streams respectivelydirected through the plurality of exhaust after-treatment units; and theplurality of exhaust after-treatment units are attached to the isolatorsabove the base.